1. Field of the Invention
The present invention relates to a contactless capacitor discharge type ignition system for an internal combustion engine, especially to a contactless ignition system which permits both spark advance and retard.
2. Description of Prior Art
In a conventional contactless capacitor discharge type ignition system, in which a timing signal is obtained by a transformer connected across a capacitor charging coil using a half wave in a negative derection which is not used for charging a capacitor, as exemplified in U.S. Pat. No. 3,809,043 granted to present inventor, only a spark advance can be carried out.
However, recently an ignition system is required to carry out a spark retard during a relatively high-speed operation of an engine, so that an engine for a motor cycle, especially for a motor cycle used for a motor race, can produce a larger output power more effectively while it is operated at a relatively high-speed. In another aspect, to prevent abnormally high-speed running of an engine, retarding the spark timing is effective.